org.apache.commons.collections4.map
Class TransformedMap<K,V>

java.lang.Object
  extended by org.apache.commons.collections4.map.AbstractIterableMap<K,V>
      extended by org.apache.commons.collections4.map.AbstractMapDecorator<K,V>
          extended by org.apache.commons.collections4.map.TransformedMap<K,V>
All Implemented Interfaces:
Serializable, Map<K,V>, Get<K,V>, IterableGet<K,V>, IterableMap<K,V>, Put<K,V>
Direct Known Subclasses:
TransformedSortedMap

public class TransformedMap<K,V>
extends AbstractMapDecorator<K,V>
implements Serializable

Decorates another Map to transform objects that are added.

The Map put methods and Map.Entry setValue method are affected by this class. Thus objects must be removed or searched for using their transformed form. For example, if the transformation converts Strings to Integers, you must use the Integer form to remove objects.

Note that TransformedMap is not synchronized and is not thread-safe. If you wish to use this map from multiple threads concurrently, you must use appropriate synchronization. The simplest approach is to wrap this map using Collections.synchronizedMap(Map). This class may throw exceptions when accessed by concurrent threads without synchronization.

This class is Serializable from Commons Collections 3.1.

Since:
3.0
Version:
$Id: TransformedMap.java 1491944 2013-06-11 20:29:22Z tn $
See Also:
TransformedSplitMap, Serialized Form

Nested Class Summary
 
Nested classes/interfaces inherited from interface java.util.Map
Map.Entry<K,V>
 
Field Summary
protected  Transformer<? super K,? extends K> keyTransformer
          The transformer to use for the key
protected  Transformer<? super V,? extends V> valueTransformer
          The transformer to use for the value
 
Constructor Summary
protected TransformedMap(Map<K,V> map, Transformer<? super K,? extends K> keyTransformer, Transformer<? super V,? extends V> valueTransformer)
          Constructor that wraps (not copies).
 
Method Summary
protected  V checkSetValue(V value)
          Override to transform the value when using setValue.
 Set<Map.Entry<K,V>> entrySet()
           
protected  boolean isSetValueChecking()
          Override to only return true when there is a value transformer.
 V put(K key, V value)
          Note that the return type is Object, rather than V as in the Map interface.
 void putAll(Map<? extends K,? extends V> mapToCopy)
           
static
<K,V> TransformedMap<K,V>
transformedMap(Map<K,V> map, Transformer<? super K,? extends K> keyTransformer, Transformer<? super V,? extends V> valueTransformer)
          Factory method to create a transforming map that will transform existing contents of the specified map.
static
<K,V> TransformedMap<K,V>
transformingMap(Map<K,V> map, Transformer<? super K,? extends K> keyTransformer, Transformer<? super V,? extends V> valueTransformer)
          Factory method to create a transforming map.
protected  K transformKey(K object)
          Transforms a key.
protected  Map<K,V> transformMap(Map<? extends K,? extends V> map)
          Transforms a map.
protected  V transformValue(V object)
          Transforms a value.
 
Methods inherited from class org.apache.commons.collections4.map.AbstractMapDecorator
clear, containsKey, containsValue, decorated, equals, get, hashCode, isEmpty, keySet, remove, size, toString, values
 
Methods inherited from class org.apache.commons.collections4.map.AbstractIterableMap
mapIterator
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
 

Field Detail

keyTransformer

protected final Transformer<? super K,? extends K> keyTransformer
The transformer to use for the key


valueTransformer

protected final Transformer<? super V,? extends V> valueTransformer
The transformer to use for the value

Constructor Detail

TransformedMap

protected TransformedMap(Map<K,V> map,
                         Transformer<? super K,? extends K> keyTransformer,
                         Transformer<? super V,? extends V> valueTransformer)
Constructor that wraps (not copies).

If there are any elements already in the collection being decorated, they are NOT transformed.

Parameters:
map - the map to decorate, must not be null
keyTransformer - the transformer to use for key conversion, null means no conversion
valueTransformer - the transformer to use for value conversion, null means no conversion
Throws:
IllegalArgumentException - if map is null
Method Detail

transformingMap

public static <K,V> TransformedMap<K,V> transformingMap(Map<K,V> map,
                                                        Transformer<? super K,? extends K> keyTransformer,
                                                        Transformer<? super V,? extends V> valueTransformer)
Factory method to create a transforming map.

If there are any elements already in the map being decorated, they are NOT transformed. Contrast this with transformedMap(Map, Transformer, Transformer).

Type Parameters:
K - the key type
V - the value type
Parameters:
map - the map to decorate, must not be null
keyTransformer - the transformer to use for key conversion, null means no transformation
valueTransformer - the transformer to use for value conversion, null means no transformation
Returns:
a new transformed map
Throws:
IllegalArgumentException - if map is null
Since:
4.0

transformedMap

public static <K,V> TransformedMap<K,V> transformedMap(Map<K,V> map,
                                                       Transformer<? super K,? extends K> keyTransformer,
                                                       Transformer<? super V,? extends V> valueTransformer)
Factory method to create a transforming map that will transform existing contents of the specified map.

If there are any elements already in the map being decorated, they will be transformed by this method. Contrast this with transformingMap(Map, Transformer, Transformer).

Type Parameters:
K - the key type
V - the value type
Parameters:
map - the map to decorate, must not be null
keyTransformer - the transformer to use for key conversion, null means no transformation
valueTransformer - the transformer to use for value conversion, null means no transformation
Returns:
a new transformed map
Throws:
IllegalArgumentException - if map is null
Since:
4.0

transformKey

protected K transformKey(K object)
Transforms a key.

The transformer itself may throw an exception if necessary.

Parameters:
object - the object to transform
Returns:
the transformed object

transformValue

protected V transformValue(V object)
Transforms a value.

The transformer itself may throw an exception if necessary.

Parameters:
object - the object to transform
Returns:
the transformed object

transformMap

protected Map<K,V> transformMap(Map<? extends K,? extends V> map)
Transforms a map.

The transformer itself may throw an exception if necessary.

Parameters:
map - the map to transform
Returns:
the transformed object

checkSetValue

protected V checkSetValue(V value)
Override to transform the value when using setValue.

Parameters:
value - the value to transform
Returns:
the transformed value
Since:
3.1

isSetValueChecking

protected boolean isSetValueChecking()
Override to only return true when there is a value transformer.

Returns:
true if a value transformer is in use
Since:
3.1

put

public V put(K key,
             V value)
Description copied from interface: Put
Note that the return type is Object, rather than V as in the Map interface. See the class Javadoc for further info.

Specified by:
put in interface Map<K,V>
Specified by:
put in interface Put<K,V>
Overrides:
put in class AbstractMapDecorator<K,V>
See Also:
Map.put(Object, Object)

putAll

public void putAll(Map<? extends K,? extends V> mapToCopy)
Specified by:
putAll in interface Map<K,V>
Specified by:
putAll in interface Put<K,V>
Overrides:
putAll in class AbstractMapDecorator<K,V>
See Also:
Map.putAll(Map)

entrySet

public Set<Map.Entry<K,V>> entrySet()
Specified by:
entrySet in interface Map<K,V>
Specified by:
entrySet in interface Get<K,V>
Overrides:
entrySet in class AbstractMapDecorator<K,V>
See Also:
Map.entrySet()


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